Mechanical closure with slit carrier for disposable diapers

ABSTRACT

An extensible tab fastener for a disposable diaper comprises a laminate of an extensible facestock and an ordinarily nonextensible mechanical fastener. The nonextensible mechanical fastener is rendered extensible by providing in at least the nonextensible portions thereof a plurality of separation interfaces or parting planes extending through the thickness of the nonextensible portion or portions at spaced locations in the direction of desired extensibility.

This application claims the priority of U.S. Provisional applicationSer. No. 60/010,075, filed Jan. 16, 1996.

BACKGROUND OF THE INVENTION AND RELATED ART

The present invention relates to closures for fastening adjacentportions or edges of materials together. The closures are useful asfastening system closures for disposable diapers.

Diapers of this general type are widely used. A typical diaperconstruction comprises an absorbent pad or batt or the like enclosed inan outer plastic shell or a non-woven backsheet that is non-woven fabriclaminated with a water impermeable layer such as a polyethylene film. Awater permeable inner shell or liner is also provided to promoteseparation of fluid from the user.

The fastener tape system generally includes adhesive tabs fastened toone end of the diaper assembly construction at each lateral side of thediaper in a permanent "factory joint" by the diaper manufacturer usingadhesives or other techniques. Heretofore, the tabs typically have aface coated with pressure-sensitive adhesive. The tabs are releasablyattachable to the other end of the diaper at each lateral side in a"user joint". The attachment is releasable both to allow permanentremoval of the diaper and to allow unfastening to inspect the diaperfollowed by refastening if indicated.

There is a need for a diaper tab having a user joint with a mechanicalclosure, and more particularly, an extensible or stretchable tab havingsuch a mechanical closure. Such closures may include Velcro brandclosures with mechanical engaging elements. The tab may engage aspecially constructed mechanical receiving or engaging location at alanding member or the non-woven backsheet of a disposable diaper. Suchmechanical closure members are typically nonextensible since theintegral substrate and engaging elements are formed of relatively stiffand nonextensible materials or plastics. These nonextensible materialsare used to assure that the engaging elements provide adequate strengthand do not merely bend or flex with disengagement loads.

The use of combined adhesive and mechanical fastener systems is shown inU.S. Pat. Nos. 5,019,065, 5,053,028 and 4,869,724. The teachings of allof these patents being incorporated herein by reference.

Related art includes U.S. Pat. Nos. 4,795,456 and 4,834,820.

SUMMARY OF THE INVENTION

The present invention provides an extensible tab fastener system havinga user joint that enables mechanical attachment. An extensible facestockcooperates with an ordinarily nonextensible mechanical fastener to formthe extensible tab fastener in accordance with the present invention.The nonextensible mechanical fastener is rendered extensible byproviding in at least the nonextensible portions thereof a plurality ofseparation interfaces or parting planes extending through the thicknessof the nonextensible portion or portions at spaced locations in thedirection of desired extensibility. The tab fastener system may beproduced by high speed manufacturing processes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing apparatus for making stock forconversion to a diaper tab in accordance with the present invention; and

FIG. 2 is a perspective view showing a tab fastener applied to a diaperwith the tab in the deployed position ready for closure.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the production of stock for a diaper tab 10 isschematically shown in a single width size for convenience ofillustration. As indicated in dotted outline, the diaper tab 10 isformed by cutting the stock across its width in the cross direction.

Referring to FIG. 2, the diaper tab 10 is shown deployed for closure ofa diaper 12. The diaper tab 10 includes a facestock film 14, amechanical engagement or closure member 16 having a substrate 18 andprotuberances or projecting elements 20 extending therefrom.

The facestock film 14 is extensible or stretchable. It may be separatelyformed by any suitable process and subsequently joined with the otherlayer portions of the tab 10, or it may be directly extruded onto thesubstrate 18 of the member 16. The facestock film 14 may be formed ofelastomers such as the thermoplastic elastomers sold by the ShellChemical Company under the designations Kraton. These elastomers may beSBS, SIS, SI, S(IS)_(X) and SEBS block copolymers and mixtures thereof.The facestock may also comprise a polyurethane polymer of suitableelastic characteristics. Also, the facestock may be a stretchablenon-woven fabric.

The facestock film 14 is joined to the member 16 by sonic welding, a hotmelt adhesive or any other convenient manner to provide a permanentbond. In FIG. 1, a sonic welder 22 is shown in the production line forjoining the facestock film 14 to the member 16. Alternatively, apressure-sensitive adhesive may be used, such as an acrylic or a rubberpressure-sensitive adhesive as are well known in the art. Typicalpressure-sensitive adhesives include acrylic resin and natural orsynthetic based rubber adhesives. Preferred adhesives include hot meltpressure-sensitive adhesives of the A-B-A block copolymer type asdisclosed in U.S. Pat. No. 3,932,328. Illustrative rubber basedadhesives include styrene-isoprene-styrene and styrene-butadiene-styrenewhich may optionally contain diblock components. The adhesive may beapplied using hot-melt, solvent or emulsion techniques.

The mechanical engagement member 16 comprises any of the well known hookand loop type engagement materials as particularly exemplified by theVelcro fabric materials sold by Velcro USA. The member 16 includes asubstrate 18 and projecting elements or hooks 20. The member 16 istypically not extensible and, more particularly, the substrate 18 is notextensible since the elements 20 are discrete projections extending fromthe substrate. The elements 20 together with the member 16 may be formedof polypropylene, nylon, polyester or other relatively rigid polymer.

The mechanical elements 20 are integrally formed with the substrate 18in the illustrated embodiment. The elements 20 extend generallyperpendicular from the substrate 18. The elements 20 should be ofsufficient length to provide mechanical engagement with a locking orengaging array of mechanical elements, or with a fibrous material suchas a non-woven landing tape or member 24 as shown in FIG. 2 or anon-woven backsheet of a diaper.

Further, the polymer forming the member 16 should be of sufficientstiffness or rigidity to provide the elements 20 with the required shearstrength engagement properties.

In accordance with the invention, the member 16 and more particularlythe substrate 18 thereof is made extensible by a providing a pluralityof separation interfaces or slits 26 which form parting planes extendingthrough the thickness of the substrate at spaced locations along thelength of the tab 10. The slits 26 may be formed with accuratedimensions assuring full cutting through the thickness of the substrate18 by rotary die cutting as in the case of label preparation as is knownin the art. A rotary die cutter 28 is shown in FIG. 1 for engagementwith the substrate 18 through the elements 20. Such rotary die cuttingis a high speed process that lends itself to economic production.

The slits 26 are spaced apart a decreasing distance with decreasing sizeof the elements 20. In typical diaper tab applications, the slits 26 maybe spaced apart a distance of from about 0.1 to 0.5 inches as measuredalong the length of the tab 10 in the direction extensibility. Thisspacing may be even less for elements 20 of substantially smalldimension.

The slits 26 effectively divide the substrate 18 into parallel segments18a, 18b, 18c, etc., supported by the facestock film 14 The segments18a, 18b, 18c, etc. and associated elements 20 are separable along thelength of the tab 10 as shown in FIG. 2. This enables groups of elements20 to separate from other groups of elements 20 as the facestock 14 andtab 10 is stretched. The tab 10 is thereby provided with anextensibility substantially corresponding with that of the facestockfilm 14.

For purposes of mounting the tab 10 to the diaper 12 at the factoryjoint, the member 16 has a width slightly less than that of thefacestock film 14. The exposed proximal end (or left end in FIGS. 1 and2) of the tab 10 may then be secured to the diaper 12 in any convenientmanner by the diaper manufacturer, e.g. adhesive or sonic welding orother means.

It should be appreciated that the tab 10 in accordance with theinvention may be adhesive free in respect to both the diaper closureengagement per se and the fastener construction.

It should be evident that this disclosure is by way of example and thatvarious changes may be made by adding, modifying or eliminating detailswithout departing from the fair scope of the teaching contained in thisdisclosure. The invention is therefore not limited to particular detailsof this disclosure except to the extent that the following claims arenecessarily so limited.

What is claimed is:
 1. A disposable diaper having opposed first andsecond ends and a fastening system for releasably securing said diaperends together about a user, said fastening system including tab memberssecured to said first end of said diaper and a landing member secured tosaid second end of said diaper, said tab members and landing memberbeing adapted to mechanically engage and disengage for diaper closureand opening, each of said tab members having a length along which theyrespectively engage said landing member, each said tab member includingan extensible facestock superposed on and secured to a mechanicalfastener, said mechanical fastener being coextensive with at least aportion of said tab member, said mechanical fastener including anordinarily nonextensible substrate having opposed substrate faces, oneof said substrate faces being secured to said facestock and the other ofsaid substrate faces having discrete engagement members projectingtherefrom, said substrate having in at least a portion thereof aplurality of separation interfaces extending through the thickness ofthe substrate at spaced locations in the direction of the length of saidtab, said interfaces separating upon application of tension loads in thedirection of the length of said tab to thereby render said substrateextensible.
 2. A diaper as in claim 1, wherein said mechanical fastenercomprises a hook and loop fastener.
 3. A diaper as in claim 2, whereinsaid facestock comprises an elastomer or a stretchable non-woven fabric.4. A diaper as in claim 3, wherein said separation interfaces areprovided by slits.
 5. A diaper as in claim 3, wherein said separationinterfaces are spaced apart a distance of from about 0.1 to 0.5 inchesas measured along the length of said tab.
 6. A diaper as in claim 5,wherein said tab member has a proximal end secured to said diaper andsaid mechanical fastener overlies a portion of said tab member remote ofsaid proximal end of said tab member.
 7. A diaper as in claim 1, whereinsaid mechanical fastener substrate and engagement members are integrallyformed.
 8. A diaper as in claim 1, wherein said mechanical fastenersubstrate and engagement members are formed of a single polymer.
 9. Adiaper as in claim 1, wherein said mechanical fastener is a VELCRO®brand closure with mechnical engaging elements.